Aluminium Radiator upgrade for Fiat 124 Spider

[ricardoblack]

Hi all

I am fitting a Fiat 130 Strada engine to a Fiat 124 Spider.

Anyway I was having a look at the old rad and was thinking rather than spending money on it getting it re cored I'll get a modern Aluminium one. With a bit of reserch I found that the Volvo 240 ones fit seem well made and cost around ‚£56 new.S ounds good does't it....

Most manufacturors quote radiator core measurements height width depth.I have been multiplying these together to give me a comparison figure I'm sure this isn't the proper way to calculate radiator effective area but though it would get me in the ballpark.

What do you guys think?

By my rough calculations the Volvo rad is smaller than the Fiat one shame because the pic of the installation I found looks neat.

The Alfa 156 turbo one is bigger but I will have to get some overall measurements to see if it will fit.

One more thing you could clear up for me:
Aluminium rad manufacturors claim 20% improvement over copper core rads but I always thought copper was more efficient at getting rid of heat than Aluminium anyone got a view.

Advice based on experience very welcome please.

Regards

Rick

[ricardoblack]

I've been doing a bit of surfing re custom Aluminium rads and I've come across something else that I find rather puzzeling maybe someone can answer this one for me.
The custom made rads seem to have shrouds which are all enclosing except the apeture for the fan surely this must dramatically slow the flow rate through the rad or is this the idea?
Rick

More confused than ever....

[Evodelta]

"The custom made rads seem to have shrouds which are all enclosing except the aperture for the fan, surely this must dramatically slow the flow rate through the rad, or is this the idea? "

Not sure what you mean here, have you got a picture?

When looking into borrowing things from other cars I always find it usefull to have a browse around the local breakers yards.......

Martin.

[ricardoblack]

Hi
The back of the Radiator is compleatly covered by an aluminium shroud except for the hole for the fan.
I see an advantage at low speed in that the fan will draw air from the whole rad but I would have thought it would reduce flow at speed.
Please see pic.

Rick

[Guy Croft]

The performance would be severly impeded by the cover over the outgoing-air side, very small are for the high velocity intake air to escape plus a fan over it too.

The fan might have to be run full time to generate airflow outward from the radiator, even if it's powerful enough that's not a good idea in a car, I'd anticipate the fan motor or cabling will burn out quite soon, and I'd expect overheating all the time much over 30mph.

If the exit flow shield was an aerodynamic ducted arrangement - that might be OK - but there is never enough room for that in an engine bay and having the cover plate right over the matrix will cause real problems.

That's my appraisal, I might be wrong, if I am, sorry to the guy who made it, but with instinct for what can wrong in cars I would never start off by doing it like that, it's easy to build-in problems with the wrong basic setup; you end up redesigning the whole car in error.

GC

[SteveNZ]

Logic would suggest it would not work well. However, I know duct design is far from logical. A large funnel (inlet) design is poor as it creates a high pressure point in the funnel, making air simply flow around the funnel. A narrow aperture works better, Maybe that design works. The radiator core itself would be a restriction to airflow so a smaller aperture for exhaust air may not be a problem.

However, Id still say that specific radiator is designed to have the fan as the only source of air flow. Factory radiators sometimes have a similar design but with large exhaust flaps to allow airflow at higher speeds. At idle, when the fan operates, the flaps get sucked closed so air is pulled more uniformly through the radiator core.

[ricardoblack]

Hi All
This shrouding is not one isolated case.
Almost all the custom Radiator manufacturors do this almost total enclosure of the back of the Radiator.
Having said that my reserch has only been on the net and all these guys are in the USA.
I will try and find someone in the Uk .
This pic was taken from Ron Davis's site in the USA.

It makes no sense to me evan with the biggest fan you must be loosing at least a 3rd or more of your rad area at max flow.

Rick

[Guy Croft]

From my military days I think armoured vehicles use systems like this but the fans have to run full time.

OK maybe for circuit race, not for road, no ho, forget it.

Gc

[JB]

The ideal arrangement for a radiator, which is actually hard to achieve in a front engine car (unless your engine is under the windscreen!) but easier with side mounted radiators in a race car, is a duct. The current world rally cars all have ducted radiators.

The duct entrance is typically 50% (or less) the actual area of the radiator core and then the duct expands to the size of the core. The maximum change in duct angle is 15 degree, any more than that and the airflow becomes detached. The idea is that the duct slows down the air flow so it has more time to absorb the heat from the radiator.

On the back side of the radiator the duct narrows again to speed up the air so it exits at surrounding airspeed. If the duct arrangement is optomised it is in theory actually possible produce thrust! The thrust comes from the heat energy transfered to the air from the radiator.

I would guess that the arrangement shown in the photos is not effecient. I would prefer to see an open rear. However if I was selling a radiator I would want the customer to be happy and that means a radiator that works so why then add something that would prevent the radiator working to its optimum? Maybe these people know something we dont!



John

[ricardoblack]

The Ron Davis site I believe make rads for Nascar and other race applications. It must be to either to slow flow at high speed to improve heat transfer. Or speed it up with a venturi affect?
Either way I will email a few and try and get an answer .

Regards

Rick

[SteveNZ]

I do not agree with the comments "slowing the air down to increase heat transfer"

Heat transfer is proportional to the temperature gradient, area and heat transfer coefficient. Time, is not a factor.

Velocity is a component that makes up the heat transfer coefficient. Basically the higher the velocity the larger the heat transfer coefficient. The trade off is pressure drop, which is not important in this case.

The core design can manipulate the air velocity to some extent too.

[Guy Croft]

This discussion is interesting up to a point. Whether it leads the poster to determine what he needs will become clear in due course..

But.

Before the references to another person's product go too far (see rules re vendors in GC V/W) could someone ask Ron Davis the science behind the shrouding please on his product? Until then we will terminate the generalised discussion about his products.

I should much prefer someone with direct personal experience of what is needed to step forward with solution and reasons. Me I'd just go to professionals Pace or Brise and ask them what to do, period, and pay what it takes.

Do not take issue with my post please.

GC